Variable velocity ratio gearing



Feb. 2o, 1923. Y19,446,294. i

F. J. HEAI EY.

VARIABLE VELOGIT'YRlO GARIN'G.

man JUNE' '29. 1920. z snms-snm1- A TTY.-

Feb. 20, v11923.

F. 1. HEALEY.

VARIABLE VELOCITY RATIO GEARING.

2 SHEETS-SHEET 2.

FILE/D JUNE 29.1920.

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Patented Feb.. Ztl), i923.

FRANCIS JEREMIAI-I HEALEY, OF LONDON, ENGLAND, ASSIGNOR 'I'O THE HEALEY SYNDICATE LIIITEID,l 0F LONDON, ENGLAND, A BRITISH LIMITED LIABILITY COMPANY.

VARIABLE VELCCITY RATIO GEARING.

Application led June 29,

T 0 aZZ 'whom t may concern:

Be it kno-wn that l, FRANCIS JEREMIAH HEALEY, a subject of the King of Great Britain and Ireland, residing at 33 Poultry, in the city of London, England, have invented new and useful Improvements in and Relating to Variable Velocity Ratio Gearing, of which the following is a specification.

This invention relates to velocity ratio gearing particularly applicable to `motor cars, aeroplanes, stationary machinery of. all kinds and the like, has particular reference to gearing` involving a single chain and has for its object the provision of means whereby low weight, small initial cost, high eiiiciency, and great robustness'of construey tion are obtained in this class of gear.

The invention consists in the arrangement of an eXpansible and con-tractible driving sprocket in association with an expansible and contractible driven sprocket both sprockets being` disposed in one plane and upon parallel shafts7 said sprockets being adapted to be operatively engaged by an endless chain of predetermined and `constant length, means adapted to simultaneously expand and contract the driving and driven sprockets respectively and vice versa, means adapted to enable the individual tooth or a series of two or more teeth to be temporarily displaced relative to their driving position during the expanding or contracting operation while said teeth are in engagement with the chain. means adapted to return said individual teeth or series ofy teeth to a predetermined position upon disengagement from the chain, means associated with the teeth or series of' teeth adapted to transmit power from vthe chain to the shaft of the sprocket and vice versa and means adapted to maintain both sprockets at definite predetermined diameters.

In order that the invention may be the bet ter understood l will now proceed to describe the same in relation to the accompanying drawings, reference being had to the letters and `figures marked thereon.

1920. Serial No, 392,778.

Like letters refer to like parts in the various figures in which Fig. l. shows the parts displaced during the diameter changing operation.

Fig. 2.y shows the parts in the driving position.

Fig. 3 is an end cross sectional elevation of one of the sprockets illustrated in Fig. l, and

Fig. 4 illustrate diagrammatically a system of operating gear suitable for use with the arrangements indicated in the preceding figures. y

ln the drawings which illustrate by Way of example how the invention may be carried into eifect the rim of each sprocket c is divided up into eight segments Z, all of which are provided with teeth c of such form may be suitable to engage with the chain CZ. Each segment b has its movement so constrained as to maintain the teeth c thereon normal to the axis of the shaft e and is carried on and supported by a block f which is provided with an angularly disposed keyway g of T-crosssection. All the keyways g are engaged by angularly disposedkeys ZL of T-section attached to or formed integrally with the bush y" of the expanding and contracting device y'.

To enable expansion or contraction of suoli a sprocket c the teeth c of which are engaged by a chain (Z to be effected, each toothed segment b is slidingly mounted on its-associated block f in such manner that its possible displacement is limited to movement of a circumferential character relative to the sprocket a as a whole, Within predetermined limits, and under spring or other elastic or yielding control which is effected in the c `following` manner: Each toothed segment on the surface remote from that carrying the teeth c is provided with a projection Z2 having inclined sides 7s which engage with the inclined sides Z of the plunger Z. The plunger Z is recessed to receive a springv m which acting against the block f as an abutment tends to force the plunger Z away from the centre of the sprocket o and maintain the segments Z) in position by the interaction of the inclined sides 7c Z. The normal driving position of any segment Z; is when the projection c formed on oiattached to it is in contact with one ot' the surfaces f ot the block f associa-ted therewith.

Upon movement of the expanding and contracting device y' along the longitudinal axis oit the shaft c the angularly disposed keys it engaging with their respective keyways f/ cause the blocks f and segments Z) associated therewith to move radially and normally to the axis of the shaft e.

In the foregoing description only one sprocket a and expanding and contracting device y' has been described but it is obvious that two such sprockets and attendant devices must be associated together and dis posed in proper relation one to the other as for example the arrangement illustrated in Fig. il.

In this arrangement the operating means` include a lever n which is pivoted at In' between the shafts c e so that upon 1nove ment of the said lever n the expanding and contracting devices j y' associated with each sprocket a operates in opposite manner and expands one sprocket a while contracting the other.

It is obvious that the elfective pitch circumference of the sprockets L a when driving must be an integral number of pitch distances and in order to enable the positions of the expanding and contracting devices j to be easily adjusted so as to obtain this relation a notched segment o may be disposed in proximity to the operating lever p associated with the lever n and provided with a latch p to engage the notches 0 in the segment 0.

In use when the diameters of the sprockets c a are so selected that the circumferences are substantially equal to an integral number of pitch lengths all the' segments engaged by the chain al are displaced until the projections 7c contact with one o t the surfaces f f ot the recesses formed in the blocks f and it will be in this position that the normal drive is effected. llVhen it is desircd to vary the velocity ratio ot the shafts e c: the lever p is moved along the notched segment o until the latch p engages with the desired notch 0'; this movement olf the lever y) will through the intermediation of the lever a vary the positions oil: the devices j j thus expanding one sprocket c and contracting the other.

Obviously during the change from one pitch diameter to another the pitch circumference will not comply withthe requirements that it shall involve an integral number of pitch lengths and in order to enable the chain d to properly mesh with the engaged teeth c all the segments l) (except one) carrying such teeth are temporarily displaced rom their normal driving positions the unaiected segment l) instantaneously transmitting the whole load as shown in Fig. l. As the sprocket t rotates this segnient is disengaged from the chain d and lassumes its tree position, the load being transferred to the next segment l) following which in turn is released the sequence of operations being continued until a pitch circumference having an integral number of pitch lengths is obtained.

It will readily be seen that by this arrangement or the addition to and subtraction from the number of teeth c simultaneously' engaged by the chain al any variation of the diameter of the sprocket a within practical limits can be effected and that the number of segments Zn employed, the number of teeth c on each segment or their elimination altogether from some segments when desired, the type of yielding resistance described and the construction and details of the operating gear can all be modied or varied to suit any particular desired applicationwithout departure from the spirit ot the invention.

It is also obvious that a friction clutch or the like may be provided between the source of power and the driving sprocket it so desired and said friction clutch or the like may be adapted to be operated as and when necessary by the operating lever.

I claim v l. A variable velocity ratio gearing comprising an expansible and contractible driving sprocket, an expansible and contractible driven sprocket, an endless chain of predetermined and constant length, means adapted to simultaneously expand and contract the driving and driven sprockets respectively and vice versa, means adapted to enable an individual tooth or a series ot teeth to be temporarily circumterentially displaced relative to their normal driving position by the chain during the expanding and contracting operation, means adapted to return saidindividual tooth or series of teeth to a predetermined position located intermediate of the ends ot the possible travel upon disengagement from the chain, means associated with the teethor series ot teeth adapted to transmit power from the chain to the shatt oi? the sprocket and vice versa and .means adapted to maintain both the driving and driven sprockets at definite predetermined diameters, substantially! as described.

2. In a variable velocity ratio gearing as claimed in claim l, movable segments carrying the sprockets, blocks having keyways therein for supporting said segments, spring-urged devices carried by said blocks iis and having inclined planes adapted to engage the inclined planes on the segments, means for limiting the movement of the segments relative to the blocks, a plurality of inclined keys adapted to engage said blocks and control the movement thereof radially of the sprocket axis, means adapted to define the radial movement of said blocks, and a bushing adapted to support and simultaneously move all the inclined keys a l0 similar amount, substantially as described. In Witness whereof I have signed my name to this specification in the presence of tivo subscribing Witnesses FRANCIS JEREMIAH HEALEY. Witnessesz Dems HITCHCOCK, OLIVE WEST. 

